1. Field of the Invention
This invention relates to an improvement of an apparatus for electrically transferring a toner image from an intermediate support surface onto a final support material, and more particularly, to an image transfer complementary apparatus for an electrophotographic copying machine.
2. Description of Prior Art
Generally in an electrostatic recording system of this type, an optical system is first utilized to form an electrostatically charged latent image, which will hereinafter be called the "latent image", on the surface of a recording element such as a photosensitive plate moving on a predetermined orbit at a predetermined speed. A developer is then contacted lightly with this latent image to form a toner image and the developed toner image is then electrostatically transferred from the plate onto the surface of an image transfer sheet by means of a transfer electrode. This transfer sheet is thereafter isolated from the surface of the recording element, and the transfer sheet carrying the toner image is eventually heated so that the toner image is melted and fixed on the transfer sheet.
The greatest factor for determining the quality of the copies obtained by the present electrostatic recording system depends upon the condition of the transferring operation of the image transfer apparatus for electrostatically transferring the toner image onto a transfer sheet transported onto the recording element.
One factor affecting the quality of the image transfer is the degree of contact between of the recording element formed with the toner image thereon and the surface of the image transfer sheet, i.e., with the transferred surface of the transfer sheet. Conventionally the recording surface is electrostatically charged to attract the transfer sheet onto the recording surface, but since such mere attracting action does not contribute sufficiently to the transferring efficiency, an improvement of this technology has been proposed by the provision of a guide plate for directing the transfer sheet which is transported from the stacked position by the sheet transporting device toward the surface of the recording element, to semi-forcibly introduce the sheet. Thus, the transferring efficiency can be considerably improved, but even this technical means inevitably tend at present to damage the recording element, or the photosensitive plate and also to abruptly lower the transferring efficiency.